'use client';

import { useMemo, useState } from 'react';
import Link from 'next/link';
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
import {
  AlertTriangle,
  CheckCircle2,
  ExternalLink,
  FileSignature,
  Loader2,
  RefreshCw,
  Upload,
  XCircle,
} from 'lucide-react';
import { toast } from 'sonner';

import { Badge } from '@/components/ui/badge';
import { Button } from '@/components/ui/button';
import { Skeleton } from '@/components/ui/skeleton';
import { ExternalEoiUploadDialog } from '@/components/interests/external-eoi-upload-dialog';
import { SigningProgress } from '@/components/documents/signing-progress';
import { apiFetch } from '@/lib/api/client';
import { toastError } from '@/lib/api/toast-error';
import { cn } from '@/lib/utils';
import { useUIStore } from '@/stores/ui-store';

interface InterestContractTabProps {
  interestId: string;
  clientId: string | null;
}

interface DocumentRow {
  id: string;
  documentType: string;
  title: string;
  status: 'draft' | 'sent' | 'partially_signed' | 'completed' | 'expired' | 'cancelled';
  createdAt: string;
  signers?: Array<{ status: string }>;
}

interface DocumentSigner {
  id: string;
  signerName: string;
  signerEmail: string;
  signerRole: string;
  signingOrder: number;
  status: string;
  signedAt?: string | null;
}

const STATUS_LABELS: Record<DocumentRow['status'], string> = {
  draft: 'Draft',
  sent: 'Awaiting signatures',
  partially_signed: 'Partially signed',
  completed: 'Signed',
  expired: 'Expired',
  cancelled: 'Cancelled',
};

const STATUS_TONES: Record<DocumentRow['status'], string> = {
  draft: 'bg-slate-100 text-slate-700',
  sent: 'bg-blue-100 text-blue-700',
  partially_signed: 'bg-amber-100 text-amber-800',
  completed: 'bg-emerald-100 text-emerald-700',
  expired: 'bg-rose-100 text-rose-700',
  cancelled: 'bg-slate-200 text-slate-600',
};

const ACTIVE_STATUSES = new Set<DocumentRow['status']>(['draft', 'sent', 'partially_signed']);

/**
 * Dedicated Contract workspace tab. Mirrors the EOI tab pattern but
 * for sales contracts. Contracts differ from EOIs in that there's no
 * standard Documenso template — each contract is drafted custom per
 * deal. So the active flows are:
 *
 *   1. **Upload paper-signed copy** — the signed contract was handled
 *      outside the system; rep uploads the PDF for the record.
 *
 *   2. **Upload draft for Documenso signing** — rep uploads the PDF
 *      draft, configures signers + signing order + signature field
 *      placement, then sends via Documenso. (Recipient configurator
 *      and field-placement UI are the bigger pieces; for v1 a default
 *      footer-anchored signature layout is used.)
 *
 * The Documents tab still shows every contract document (signed or
 * drafted) as a permanent history.
 */
export function InterestContractTab({ interestId, clientId: _clientId }: InterestContractTabProps) {
  const portSlug = useUIStore((s) => s.currentPortSlug);
  const [uploadSignedOpen, setUploadSignedOpen] = useState(false);
  const [uploadForSigningOpen, setUploadForSigningOpen] = useState(false);

  const { data: docsRes, isLoading: docsLoading } = useQuery<{ data: DocumentRow[] }>({
    queryKey: ['documents', { interestId, documentType: 'contract' }],
    queryFn: () =>
      apiFetch<{ data: DocumentRow[] }>(
        `/api/v1/documents?interestId=${interestId}&documentType=contract`,
      ),
  });

  const docs = docsRes?.data ?? [];
  const activeDoc = useMemo(() => docs.find((d) => ACTIVE_STATUSES.has(d.status)) ?? null, [docs]);
  const completedDocs = useMemo(() => docs.filter((d) => !ACTIVE_STATUSES.has(d.status)), [docs]);

  return (
    <div className="space-y-5">
      {docsLoading ? (
        <Skeleton className="h-44 w-full rounded-lg" />
      ) : activeDoc ? (
        <ActiveContractCard
          doc={activeDoc}
          portSlug={portSlug ?? null}
          onUploadSigned={() => setUploadSignedOpen(true)}
        />
      ) : (
        <EmptyContractState
          onUploadSigned={() => setUploadSignedOpen(true)}
          onUploadForSigning={() => setUploadForSigningOpen(true)}
        />
      )}

      {completedDocs.length > 0 && (
        <section className="rounded-lg border bg-background">
          <header className="flex items-center justify-between border-b px-4 py-2.5">
            <h3 className="text-xs font-semibold uppercase tracking-wide text-muted-foreground">
              Contract history
            </h3>
            <span className="text-xs text-muted-foreground">
              {completedDocs.length} {completedDocs.length === 1 ? 'document' : 'documents'}
            </span>
          </header>
          <ul className="divide-y">
            {completedDocs.map((d) => (
              <li key={d.id} className="flex items-center gap-3 px-4 py-2.5 text-sm">
                <StatusBadge status={d.status} />
                <span className="flex-1 truncate font-medium">{d.title}</span>
                <span className="text-xs text-muted-foreground">
                  {new Date(d.createdAt).toLocaleDateString()}
                </span>
                {portSlug && (
                  <Link
                    // eslint-disable-next-line @typescript-eslint/no-explicit-any
                    href={`/${portSlug}/documents/${d.id}` as any}
                    className="text-xs text-primary hover:underline inline-flex items-center gap-1"
                  >
                    Open
                    <ExternalLink className="size-3" />
                  </Link>
                )}
              </li>
            ))}
          </ul>
        </section>
      )}

      {/* Reuses the external-EOI upload dialog. The endpoint
          `/api/v1/interests/{id}/external-eoi` is EOI-specific today
          — for contract paper-uploads we'll need the equivalent
          contract endpoint (deferred to a follow-up; the dialog UI
          is the pattern we'll clone). For now the flow is documented
          as 'coming soon' rather than misrouting through EOI. */}
      {uploadSignedOpen && (
        <ExternalEoiUploadDialog
          open={uploadSignedOpen}
          onOpenChange={setUploadSignedOpen}
          interestId={interestId}
        />
      )}

      {/* Upload-for-Documenso-signing dialog placeholder. The real
          dialog (PDF picker + recipient configurator + send button)
          is part of the larger custom-doc-upload service that's a
          follow-up. For now show a friendly "coming soon" card. */}
      {uploadForSigningOpen && (
        <ComingSoonDialog
          open={uploadForSigningOpen}
          onOpenChange={setUploadForSigningOpen}
          title="Send contract for signing"
          body="Upload-and-send-via-Documenso for contracts is being built. For now, draft the contract externally, get it signed via paper or another tool, then upload the signed copy here."
        />
      )}
    </div>
  );
}

// ─── Active contract hero ────────────────────────────────────────────────────

function ActiveContractCard({
  doc,
  portSlug,
  onUploadSigned,
}: {
  doc: DocumentRow;
  portSlug: string | null;
  onUploadSigned: () => void;
}) {
  const queryClient = useQueryClient();

  const { data: signersRes, isLoading: signersLoading } = useQuery<{ data: DocumentSigner[] }>({
    queryKey: ['documents', doc.id, 'signers'],
    queryFn: () => apiFetch<{ data: DocumentSigner[] }>(`/api/v1/documents/${doc.id}/signers`),
    refetchInterval: 30_000,
  });

  const signers = signersRes?.data ?? [];
  const signedCount = signers.filter((s) => s.status === 'signed').length;
  const totalCount = signers.length;
  const allSigned = totalCount > 0 && signedCount === totalCount;

  const cancelMutation = useMutation({
    mutationFn: () => apiFetch(`/api/v1/documents/${doc.id}/cancel`, { method: 'POST', body: {} }),
    onSuccess: () => {
      queryClient.invalidateQueries({ predicate: (q) => q.queryKey[0] === 'documents' });
      toast.success('Contract cancelled.');
    },
    onError: (err) => toastError(err),
  });

  const remindAllMutation = useMutation({
    mutationFn: () => apiFetch(`/api/v1/documents/${doc.id}/remind`, { method: 'POST', body: {} }),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['documents', doc.id, 'signers'] });
      toast.success('Reminder sent.');
    },
    onError: (err) => toastError(err),
  });

  return (
    <section className="rounded-xl border bg-gradient-brand-soft p-5 shadow-xs">
      <header className="flex items-start justify-between gap-3">
        <div className="min-w-0 flex-1 space-y-1">
          <div className="flex items-center gap-2 flex-wrap">
            <FileSignature className="size-4 text-foreground" />
            <h2 className="truncate text-base font-semibold text-foreground">{doc.title}</h2>
            <StatusBadge status={doc.status} />
          </div>
          <p className="text-xs text-muted-foreground">
            Created {new Date(doc.createdAt).toLocaleDateString()} ·{' '}
            {totalCount > 0 ? `${signedCount} of ${totalCount} signed` : 'No signers loaded'}
          </p>
        </div>
        <div className="flex shrink-0 items-center gap-1">
          {portSlug && (
            <Button asChild variant="outline" size="sm" className="gap-1.5 [&_svg]:size-3.5">
              <Link
                // eslint-disable-next-line @typescript-eslint/no-explicit-any
                href={`/${portSlug}/documents/${doc.id}` as any}
              >
                Open
                <ExternalLink />
              </Link>
            </Button>
          )}
          {!allSigned && (
            <Button
              variant="outline"
              size="sm"
              disabled={remindAllMutation.isPending}
              onClick={() => remindAllMutation.mutate()}
              className="gap-1.5 [&_svg]:size-3.5"
            >
              {remindAllMutation.isPending ? <Loader2 className="animate-spin" /> : <RefreshCw />}
              Remind all
            </Button>
          )}
        </div>
      </header>

      <div className="mt-4 rounded-lg border bg-background p-4">
        <h3 className="mb-3 text-xs font-semibold uppercase tracking-wide text-muted-foreground">
          Signing progress
        </h3>
        {signersLoading ? (
          <div className="flex items-center gap-2 text-sm text-muted-foreground">
            <Loader2 className="size-3.5 animate-spin" /> Loading signers…
          </div>
        ) : signers.length === 0 ? (
          <p className="text-sm text-muted-foreground italic">
            Documenso hasn&apos;t reported signers yet — check back in a moment.
          </p>
        ) : (
          <SigningProgress documentId={doc.id} signers={signers} />
        )}
      </div>

      <footer className="mt-3 flex flex-wrap items-center justify-between gap-2 text-xs text-muted-foreground">
        <p className="flex items-center gap-1.5">
          <AlertTriangle className="size-3 text-amber-600" />
          Reminders are rate-limited (max once per 7 days per signer).
        </p>
        <div className="flex items-center gap-1">
          <Button
            type="button"
            variant="ghost"
            size="sm"
            onClick={onUploadSigned}
            className="h-7 gap-1.5 text-xs [&_svg]:size-3"
          >
            <Upload />
            Upload paper-signed copy
          </Button>
          <Button
            type="button"
            variant="ghost"
            size="sm"
            disabled={cancelMutation.isPending}
            onClick={() => {
              if (window.confirm('Cancel this contract? Signers will no longer be able to sign.')) {
                cancelMutation.mutate();
              }
            }}
            className="h-7 gap-1.5 text-xs text-destructive hover:text-destructive [&_svg]:size-3"
          >
            <XCircle />
            Cancel contract
          </Button>
        </div>
      </footer>
    </section>
  );
}

// ─── Empty state ─────────────────────────────────────────────────────────────

function EmptyContractState({
  onUploadSigned,
  onUploadForSigning,
}: {
  onUploadSigned: () => void;
  onUploadForSigning: () => void;
}) {
  return (
    <section className="rounded-xl border border-dashed bg-muted/20 p-8 text-center">
      <div className="mx-auto flex size-14 items-center justify-center rounded-full bg-background text-muted-foreground">
        <FileSignature className="size-6" />
      </div>
      <h2 className="mt-4 text-base font-semibold text-foreground">
        No contract in flight for this interest
      </h2>
      <p className="mt-1 text-sm text-muted-foreground">
        Sales contracts are drafted custom per deal. Either upload a paper-signed copy you handled
        externally, or upload the draft PDF and send for e-signing via Documenso.
      </p>
      <div className="mt-5 flex flex-wrap items-center justify-center gap-2">
        <Button onClick={onUploadForSigning} size="sm" className="gap-1.5">
          <FileSignature className="size-4" />
          Upload draft for signing
        </Button>
        <Button onClick={onUploadSigned} variant="outline" size="sm" className="gap-1.5">
          <Upload className="size-4" />
          Upload paper-signed copy
        </Button>
      </div>
    </section>
  );
}

// ─── Helpers ─────────────────────────────────────────────────────────────────

function StatusBadge({ status }: { status: DocumentRow['status'] }) {
  return (
    <Badge
      variant="outline"
      className={cn(
        'border-transparent text-[10px] font-semibold uppercase tracking-wide',
        STATUS_TONES[status],
      )}
    >
      {status === 'completed' && <CheckCircle2 className="mr-1 size-3" />}
      {STATUS_LABELS[status]}
    </Badge>
  );
}

/**
 * Placeholder for the upload-for-Documenso-signing flow until the
 * full upload + recipient + field-placement service is shipped.
 * Intentional dead-end so reps know the path exists rather than
 * misclicking and getting confusing behaviour.
 */
function ComingSoonDialog({
  open,
  onOpenChange,
  title,
  body,
}: {
  open: boolean;
  onOpenChange: (next: boolean) => void;
  title: string;
  body: string;
}) {
  if (!open) return null;
  return (
    <div
      role="dialog"
      aria-modal="true"
      className="fixed inset-0 z-50 flex items-center justify-center bg-black/40 p-4"
      onClick={() => onOpenChange(false)}
    >
      <div
        className="max-w-md rounded-lg border bg-background p-6 shadow-lg"
        onClick={(e) => e.stopPropagation()}
      >
        <h3 className="text-base font-semibold text-foreground">{title}</h3>
        <p className="mt-2 text-sm text-muted-foreground">{body}</p>
        <div className="mt-4 flex justify-end">
          <Button onClick={() => onOpenChange(false)} size="sm" variant="outline">
            Got it
          </Button>
        </div>
      </div>
    </div>
  );
}